| Mothers of Living C.I.C. | Public administration | 2023 |
| Motion Accel Robotics Limited | Professional & scientific | 2021 |
| Motion Entertainment Services Limited | Arts & recreation | 2022 |
| Motivation-Cp Limited | Education | 2016 |
| Motive Music Academy Ltd | Education | 2025 |
| Motor Ninjas Limited | Wholesale & retail | 2019 |
| Motorsport Auctions Ltd | Professional & scientific | 2013 |
| Motorsport Sales Ltd | Wholesale & retail | 2017 |
| Mouleyre Consulting Limited | Professional & scientific | 2016 |
| Mount Housing Association OT Mount Housing CIC | Real estate | 2025 |
| Mount Stuart Wealth Management Ltd | Financial services | 2014 |
| Mountaincf Limited | Professional & scientific | 2018 |
| Mousecroft House Management Company Limited | Households | 2018 |
| Move Chiropractic Limited | Health & social care | 2015 |
| Move Developments Limited | Construction | 2016 |
| Moveo Consulting Ltd | Professional & scientific | 2020 |
| Moving Forward With Jenny Limited | Health & social care | 2024 |
| MOW and Behold Limited | Administrative & support | 2026 |
| Mowbray Woodwards Limited | Professional & scientific | 2014 |
| Moweh Ltd | Administrative & support | 2023 |
| Mozu Creative Ltd | Information & communication | 2023 |
| MP Bars Limited | Hospitality | 2022 |
| MP Homes Limited | Construction | 1997 |
| MP Legal Holdco Ltd | Financial services | 2025 |
| MP Williams Landscaping Ltd | Administrative & support | 2023 |
| MPH Vehicle Solutions Limited | Administrative & support | 2008 |
| Mphdental Ltd | Health & social care | 2026 |
| MPK Vehicle Repairs Ltd | Wholesale & retail | 2018 |
| MPL Wrought Iron Cheltenham Limited | Manufacturing | 2016 |
| Mpps Group Limited | Construction | 2021 |
| MPS Fernando Limited | Real estate | 2025 |
| MPS Hospitality Limited | Hospitality | 2025 |
| MQQ 2 Limited | Wholesale & retail | 2025 |
| MR & JM Investments Ltd | Real estate | 2019 |
| MR & MRS Roofer UK Ltd | Construction | 2022 |
| MR Atilla Ltd | Hospitality | 2026 |
| MR Car Wash Limited | Administrative & support | 2024 |
| MR Juice Ltd | Manufacturing | 2025 |
| MR Mendis Limited | Transport & logistics | 2025 |
| MR Rupert’S Ltd | Wholesale & retail | 2025 |
| MR Sash Limited | Construction | 2010 |
| MR SIX Consulting Limited | Information & communication | 2007 |
| MR Wheel X Ltd | Transport & logistics | 2025 |
| MR XXL Transport Ltd | Transport & logistics | 2024 |
| Mr.Hoppers Ltd | Hospitality | 2024 |
| Mrbt Consulting Ltd | Professional & scientific | 2019 |
| MRM 47 Ltd | Professional & scientific | 2007 |
| MRS D M France-Hayhurst Foundation | Education | 2014 |
| MRS Woods Limited | Professional & scientific | 2022 |
| MRX Capital Ltd | Financial services | 2026 |
| MS Transformation Ltd | Professional & scientific | 2022 |
| MS Warner Matthews Limited | Financial services | 2016 |
| MSD Evolution Limited | Arts & recreation | 2020 |
| MSH Web Services Ltd | Wholesale & retail | 2019 |
| Msmed Ltd | Health & social care | 2019 |
| MT Alohas Limited | Financial services | 2023 |
| MTL Cheltenham Limited | Other services | 2010 |
| MTL Properties Cheltenham Limited | Real estate | 2018 |
| Mtml Ltd. | Wholesale & retail | 2010 |
| MTW Research Ltd | Information & communication | 2013 |
| MTX Associates Limited | Information & communication | 2007 |
| Muay Thai Wholesale UK Ltd | Wholesale & retail | 2024 |
| MUD Rock Limited | Water & waste | 2026 |
| Muddy Pictures Limited | Information & communication | 2023 |
| Muddylane Nutrition Ltd | Manufacturing | 2020 |
| Mudway Workman Marquee Contractors Limited | Administrative & support | 2003 |
| MUH Transformation Solutions Limited | Professional & scientific | 2024 |
| Muhammad Arslan Ijaz Ltd | Wholesale & retail | 2025 |
| MUK Microcement UK Limited | Construction | 2023 |
| Mullooly Property Group Limited | Real estate | 2024 |
| Multi Design Services Ltd. | Professional & scientific | 1995 |
| Multi Facility Services Ltd | Administrative & support | 2013 |
| Multi Trade Property Maintenance Ltd | Administrative & support | 2015 |
| Multicultural Community Heritage Association CIC | Other services | 2025 |
| Mulvaney Bookmakers Limited | Arts & recreation | 1998 |
| Mumtaz Property Ltd | Real estate | 2024 |
| Munchies Pizza 4U Ltd | Hospitality | 2016 |
| Munchies Takeaway Limited | Hospitality | 2002 |
| Mural Imagination Ltd | Information & communication | 2020 |
| Murcox Property Holdings Ltd | Real estate | 2017 |
| Murley Media Creative Limited | Information & communication | 2023 |
| Murley Media Group Limited | Financial services | 2024 |
| MURO68UK Ltd | Hospitality | 2025 |
| Murphys Dog Grooming Ltd | Professional & scientific | 2021 |
| Murray Solutions Limited | Professional & scientific | 2005 |
| Murray Taylor Corporate Advisory Ltd | Professional & scientific | 2024 |
| Murus Consultants Limited | Professional & scientific | 2020 |
| Musa Empire Limited | Information & communication | 2025 |
| Muscleverse Ltd | Wholesale & retail | 2022 |
| Musfujees Ltd | Wholesale & retail | 2025 |
| Music at Stow | Arts & recreation | 2019 |
| Music Makers Ltd | Arts & recreation | 2025 |
| Mustoe & Sons Limited | Construction | 2000 |
| Mustoes Haulage Limited | Transport & logistics | 2002 |
| Mutimer Medical Services Limited | Health & social care | 2024 |
| Mutualisation Limited | Professional & scientific | 2011 |
| MV Cleaning Limited | Administrative & support | 2022 |
| MWC Fittings Limited | Manufacturing | 1999 |
| MWC Holdings Limited | Professional & scientific | 2001 |
| MWD Landscapes Ltd | Administrative & support | 2018 |